Digitally-enhanced, Decentralized, Multi-omics Observational Cohort

Inclusion Criteria for Cohort participants: * Male or female over 45 years of age. * Subject is seen at a memory clinic or is part of an observational study. * An informant (caregiver/family member) is available to collaborate. * Diagnosis of individuals in the AD biological continuum with evidence of amyloid-beta accumulation based on the presence of Aβ load AD biomarkers (either in CSF or PET scan), MMSE, CDR score and cognitive tests as defined by the Guidance document of EMA (2016) or FDA (2018): * preclinical AD: MMSE≥27 and CDR=0, either none or borderline cognitive deficits (compatible with FDA stages 1 and 2, with positive AD biomarkers). Patients reporting subjective cognitive decline who meet the criteria above are eligible for assignment to the preclinical AD group. * prodromal AD/MCI due to AD: MMSE \>23, CDR=0.5, impairment on cognitive testing with RBANS (compatible with stage 3 FDA, with positive AD biomarkers). * Prodromal PD: Male or female age 60 years or older (except age 30 years or older for SNCA, or rate genetic mutations (such as Parkin or Pink1) participants). * Individuals taking any of the following drugs: alpha methyldopa, methylphenidate, amphetamine derivatives or modafinil, must be willing and medically able to hold the medication for at least 5 half-lives before DaTscan imaging. * Informed consent signed by the subject and informant. * Informant should be able to read and communicate in the language of the recruitment centre and available to ac…